hey, when i fly the USAF missons in the F-16 the game sais he "error loading the GPS_engine "and the flight plan will not be used. whys that?

another thing, i downloaded the arrester cables and in the file there come the files needed to install that "sonic bang" thing that u hear and see when u pass mach 1. i followed the procedures but nothing happens! whtats the speed for mach 1? isnt it about 650 knots?

oh, and another thing: when they say  "FL045", for example, what does that mean? i know its flight level (duh) but what units is that?